[ThinLTO] Fix temp file dumping, enable via llvm-lto and test it

Summary:
Fixed a bug in ThinLTOCodeGenerator's temp file dumping. The Twine
needs to be passed directly as an argument, or a copy saved into a
std::string.

It doesn't seem there are any consumers of this, so I added a new option
to llvm-lto to enable saving of temp files during ThinLTO, and augmented
a test to use it to check post-import but pre-opt bitcode.

Reviewers: mehdi_amini

Subscribers: llvm-commits, mehdi_amini

Differential Revision: https://reviews.llvm.org/D23525

llvm-svn: 278761

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/LTO/ThinLTOCodeGenerator.cpp b/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
index bfb0980bc16..9224f726cd9 100644
--- a/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
+++ b/llvm/lib/LTO/ThinLTOCodeGenerator.cpp
@@ -78,9 +78,9 @@ static void saveTempBitcode(const Module &TheModule, StringRef TempDir,
   if (TempDir.empty())
     return;
   // User asked to save temps, let dump the bitcode file after import.
-  auto SaveTempPath = TempDir + llvm::utostr(count) + Suffix;
+  std::string SaveTempPath = (TempDir + llvm::utostr(count) + Suffix).str();
   std::error_code EC;
-  raw_fd_ostream OS(SaveTempPath.str(), EC, sys::fs::F_None);
+  raw_fd_ostream OS(SaveTempPath, EC, sys::fs::F_None);
   if (EC)
     report_fatal_error(Twine("Failed to open ") + SaveTempPath +
                        " to save optimized bitcode\n");